1. Field of the Invention
The present invention relates generally to surgical instruments for occluding a vessel or other tubular structure, for grasping and retaining other body tissue, for retracting tissue at a surgical incision site, or for stabilizing tissue or bodily organs within a surgical incision site. More particularly, the invention relates to surgical instruments such as surgical clamps, surgical retractors or surgical stabilizers that include resilient filaments that abut against a vessel, tissue or organ to resist movement of the vessel, tissue or organ relative to the instrument. The invention further relates to methods of manufacturing clamp pads or members for attachment to such instruments that include such resilient filaments.
2. Description of the Related Art
Instruments for occluding blood vessels during surgery, such as conventional metal or rigid surgical clamps or clips, are well known. However, such instruments are known to cause trauma to the clamped vessel at the clamping site. A number of atraumatic instruments have been developed for reducing or eliminating the trauma to a vessel during occlusion of the vessel. U.S. Pat. No. 3,993,076 to Fogarty, et al. describes a device whereby a vessel is occluded by using a resilient tape to press a vessel against a resilient pad. However, this device suffers from the disadvantage that it slips easily. For example, the pulsations of an occluded artery can tend to force the device off of its clamped position on the occluded artery. Conventional surgical clamps have also been adapted to include jaw surfaces containing resilient members or pads. These devices likewise are prone to slipping off of the clamped vessel. This can be especially problematic in situations where, due to obstructions, a vessel has been clamped with only the distal tips of the clamp jaws. In such situations, the vessel can be especially prone to slipping in the direction of the distal tips.
Other attempts have been made to atraumatically occlude a vessel in a secure fashion. U.S. Pat. No. 3,746,002 to Haller describes a vascular clamp with resilient gripping members located on the jaws. A plurality of pin members are embedded within the gripping members, the pin members of a length such that when a vessel is clamped between the members, the resilient material deflects to accommodate the vessel, exposing the pin members which grippingly engage the outer layer of the vessel, thus securing the vessel to the gripping member. While the Haller device is less traumatic to a vessel than other occlusion devices, it nevertheless has the disadvantage of traumatizing the outer layer of the vessel.
U.S. Pat. No. 4,821,719 to Fogarty describes a vascular clamp device containing resilient pads with Velcro-like hooks. The hooks interact with the external adventitial layer of the vessel forming a cohesive-adhesive relationship with the vessel similar to the bonding of Velcro materials. While this device offers a less traumatic way to occlude a vessel, the cohesive-adhesive nature of the bond can result in the removal of some of the adventitial layer of the vessel when disengaging the device.
There is thus a need for a surgical clamp which atraumatically occludes vessels while avoiding the disadvantages previously associated with existing surgical clamps or occlusion devices.
Likewise, conventional tissue retractors are well known which retract tissue at a surgical incision site to provide a surgeon visual and mechanical access to the interior of a patient""s body. These tissue retractors employ rigid gripping members, usually of metal, to grip, retract, and retain all forms of body tissue, e.g., bone, skin, fat, or muscle, at the incision site. The disadvantages of such retractors are two-fold. First, the rigid gripping members, due to their rigidity, cause trauma to the retained tissues. Second, the gripping members are generally prone to slippage, both laterally, along the sides of the incision, and upwardly out of the incision and away from the patient""s body.
Thus, there is also a need for a surgical retractor that atraumatically, yet securely, retracts and retains tissue at a surgical incision site.
Other surgical instruments or devices are known that provide for mechanical immobilization and stabilization of tissue or organs within a surgical incision site. These instruments or devices, known as stabilizers, will immobilize, stabilize, or otherwise restrain tissue or organs by exerting pressure against a tissue or organ to hold the tissue or organ in place, aiding a surgeon performing operations on the tissue or organ. Such stabilizers have particular use in minimally invasive coronary surgery procedures. For example, coronary artery stabilizers have been used to immobilize a beating heart in order to perform coronary grafting. These stabilizers achieve immobilization largely by local myocardial compression from direct pressure applied by the stabilizer on either side of the grafted artery. These stabilizers come in a variety of shapes, including open foot-shaped devices, and rigid circle or rectangular shapes, and may be either hand held, or attached to an incisional retractor located at the incision site. Another such stabilizer device consists of a system having two fixed handles having suction cups that are positioned on either side of the vessel.
Given the amount of pressure transferred to the myocardium during the use of these stabilizers, there is a danger that the contact surfaces of these stabilizer devices will traumatize the myocardial tissue. In addition, the forces exerted by the immobilized but still beating heart can lead to a shift in alignment of the stabilizer, which can disrupt the grafting procedure. Thus, there is a need for stabilizers that atraumatically immobilize a tissue or body organ, such as the heart, and yet at the same time provide improved traction to maintain the position of the immobilized tissue or organ.
It is an object of the present invention to provide surgical instruments, including surgical clamps or other occlusion devices, surgical retractors, or surgical stabilizers having gripping surfaces and an array of resilient filaments extending at acute angles relative to the surface for engagement with vessels, tissue, or organs. The filaments terminate in free distal ends that abut against the engaged vessel, tissue or organ to resist and restrict movement of the engaged vessel, tissue or organ in a direction opposed to the orientation of the filaments. The filaments themselves can also be resiliently flexible so as to cushion the engaged vessel, tissue or organ.
In the case of a surgical clamp according to the present invention, the filaments are located on opposing jaws of a surgical clamp. When the jaws are moved toward one another to engage a vessel, some of the filaments, based on their angle of orientation in relation to the vessel, will abut against the vessel and impart a resistive force against the vessel along the direction of the filament. When the jaws of the surgical clamp are partially or fully engaged with the vessel, filaments of the lower jaw push or lever the vessel upward toward the upper jaw, while at the same time filaments of the upper jaw push or lever the vessel downward toward the lower jaw. This levering action of the filaments secures against movement of the vessel in a direction generally opposed to the orientation of particular filaments.
In one embodiment of the invention, the filaments can extend directly from the surface, which itself can be resiliently flexible. In this embodiment, when the jaws are moved toward one another to engage a vessel, some of the filaments, based on their angle of orientation in relation to the vessel, will be pressed flat against the surface which will itself deflect to accommodate the vessel in atraumatic fashion. In an alternative embodiment, the filaments can extend from along the sides of the resilient surface and the distal ends of the filaments can terminate at positions even with, above, or below the level of the surface. In this embodiment, the surface can deflect to atraumatically engage the vessel while the filaments are likewise engaging the vessel and resisting movement of the vessel in a direction opposed to the orientation of the filaments. Where the distal ends of the filaments terminate at a position below the level of the surface, the surface will deflect to a position where both the surface and the filaments will engage the vessel.
In another embodiment of the invention, the filaments can be oriented as discussed above to resist movement of the vessel in the direction of the distal ends of the surgical clamp jaws. Such an orientation is especially advantageous where, due to obstructions, a surgeon can only access and clamp a vessel with the distal tips of the surgical clamp jaws. With a conventional clamp, the vessel can slip from the clamp in the direction of the distal tips. In the above embodiment of the present invention, however, slippage of the vessel will favor the direction back toward the proximal ends of the surgical clamp jaws, thereby retaining the vessel in a clamped condition.
In another embodiment of the invention, the filaments of the upper and lower jaws of the surgical clamp are oriented to resist movement of a clamped vessel towards either the distal or the proximal ends of the jaws. The filaments can also be oriented to resist movement of a clamped vessel in a direction perpendicular to the jaws.
A surgical retractor according to the present invention likewise uses resilient surfaces with resilient filaments that engage and retract tissue. When the resilient member, or base member, containing the resilient filaments engages tissue at an incision site, the tips of some of the filaments, again based on the angle of orientation of these filaments in relation to the tissue being retracted, will abut against the tissue and impart a resistive force against the tissue along the direction of the filament. In one embodiment of the invention, the filaments can be oriented to resist movement of the retracted tissue relative to the base member in a lateral direction along the sides of the incision and in an upwardly direction away from the patient""s body.
A surgical stabilizer according to the present invention also includes surfaces having resilient filaments that engage and restrain tissue or organs. When the resilient filaments engage the target tissue or organ, the tips of some of the filaments, again based on the angle of orientation of these filaments in relation to the tissue or organ being restrained, will abut against the tissue or organ and impart a resistive force against the tissue or organ along the direction of the filament. In one embodiment of the invention, the stabilizer can have one or more stabilizing members or arms that engage the target tissue or organ. The resilient filaments of each engaging arm can be oriented to resist relative movement of the restrained tissue or organ along the arm length and/or transverse to the arm length.
It is a further object of the present invention to provide attachable pads or members for a surgical clamp or other occlusion device, surgical retractor, or surgical stabilizer that contain gripping surfaces and arrays of filaments extending at acute angles relative to the surfaces for engagement with vessels or tissue. Again, these filaments are such that when the particular device is engaged with a vessel or other tissue, the filaments abut against the vessel or tissue to resist and restrict movement of the vessel or tissue in a direction opposed to the orientation of the filaments. The filaments can extend directly from the surface of the pad or can extend from along the sides of pad. For pads having filaments extending directly from the pad surface, preferably the pad will include a resilient or elastomeric cushion having portions of the filaments embedded in the cushion itself. Optimally, the filaments are resiliently deflectable and the cushion will be softer and more easily deflected than the filaments. The characteristics of the cushion and the embedded filaments are such that the cushion and filaments work together to achieve a synergistic effect. The portion of the cushion containing the embedded filaments forms a clamping region of the cushion. The embedded filaments provide structural support to the clamping region. by reinforcing and stabilizing the region against excessive deformation, especially lateral deformation, when the pad is under a clamping load. The clamping region in turn stabilizes and orients the filaments at the desired angles relative to the pad surface to provide directional resistance against movement of engaged vessels or tissue. The clamping region performs this orientation function prior to and during the application of a clamping load to the pad. When a load is applied to the pad, the filaments and the cushion are deflected, but the clamping region stabilizes the filaments against excessive deformation and maintains the desired orientation of the filaments. The clamping region continues to perform this function as the load is released from the pad and the deflected filaments and cushion return to their original preloaded positions.
Methods of manufacturing the attachable pads or members of the present invention are also provided. According to one method, a tubular or cylindrical sleeve of woven resilient filaments is provided and a pad with a gripping surface is extended through the sleeve. The sleeve is secured to the pad opposite the gripping surface and the sleeve is then cut longitudinally along the gripping surface, releasing the resilient filaments to extend at acute angles relative to the gripping surface.